This invention relates generally to tension control systems. More particularly, the invention relates to apparatuses and methods for maintaining a constant tension in a flexible cable.
The need for an apparatus capable of creating and maintaining a constant tension is a flexible cable in acute in a wide variety of cable systems, e.g., electric trolley systems, exercise devices, and aerial tramways. In particular, these systems require apparatuses, and methods for the operation thereof, which are capable of maintaining a cable at a substantially constant tension during fluctuating climatic and loading conditions. Further, the cable tension must often be maintained within a selected, narrow range for efficient and safe operation.
Depending on the application for which it is used, flexible cabling can be formed of single or multiple strands. Further, the cabling can be spliced to form a continuous loop, as in the case of aerial tramways, or have both ends anchored, as for trolley systems. Several apparatuses have been developed to attain and maintain spliced or anchored cable at a substantially constant tension. These apparatuses include counterweighted, pneumatic, frictional, and spring-loaded assemblies. See, e.g., U.S. Pat. Nos. 3,885,789; 4,318,308; 4,470,355; 4,614,130; and 4,682,760. Although effective in many applications, these apparatuses often have severe design limitations such as massive and unwieldy weights, components which can jam or fail, e.g., pulleys and pivots, and generally slow reaction times to dynamic loadings. These limitations, as well as the economic inefficiency resulting from extended down-time for the repairs typically required to service these devices, renders them inappropriate for many uses.
It is accordingly an object of this invention to provide an apparatus and method for creating and maintaining a substantially constant force in a flexible cable.
It is another object of the invention to provide an apparatus and method that is economical to manufacture, easy to use, and that provides a reliable, substantially constant tension force in a flexible cable.
Other general and specific objects of the invention will in part be obvious and will in part appear hereinafter.